Posted by Rogervan on 12/24/2016, 6:21 pm 18.104.22.168
I've always thought ostrich eggs are made of calcium phosphate, because the people who grind filigrees on them get poisoned by the dust. Supposedly from calcium phosphate. They have to wear airtight masks.
But I guess my reasoning was wrong. It seems that eggshells contain both calcium carbonate and calcium phosphate, and they are good for use as supplements.